Physics · Science General

Acoustics and Sound Waves

2,006 Questions

Acoustics and sound waves deal with mechanical vibrations traveling through media like air and water. Key concepts include wave reflection, beats, echoes, the Mach number, and infrasound. These physics fundamentals are regularly tested in general science sections of multiple competitive exams.

Sound wave propagationEchoes and reflectionWave interferenceMach numberInfrasound frequency

Acoustics and Sound Waves Questions

Multiple choice physics sound audible, infrasonic and ultrasonic sounds different sounds range of hearing

Which of the following frequencies of sound elephants produce ?

  1. ultrasonic

  2. infrasonic

  3. both A & B

  4. cant say
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Some of the elephant's vocalizations are infrasonic, and thus are inaudible to humans. The prominence of very low frequencies in the vocalizations is a defining characteristic of all three species of elephants. Sounds are generally considered to be infrasonic if their frequency is less than $20 Hz$ (the lower limit of human hearing). Low frequency sounds travel farther than high frequency ones, which make them ideal for long distance communication.
Hence, Elephants produce infrasonic sound. 

Multiple choice physics sound audible, infrasonic and ultrasonic sounds different sounds range of hearing

Name the sounds of the frequencies given below $10Hz$.

  1. $ultrasonic$
  2. $infrasonic$
  3. $supersonic$

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Infra-sound is a low-frequency sound. It is sound that is lower in frequency than $20 \ Hz$ or cycles per second, the normal limit of human hearing. Hearing becomes gradually less sensitive as frequency decreases, so for humans to perceive infrasound, the sound pressure must be sufficiently high. The ear is the primary organ for sensing infra-sound, but at higher intensities it is possible to feel infra-sound vibrations in various parts of the body.

Multiple choice physics sound audible, infrasonic and ultrasonic sounds different sounds range of hearing

Infrasound can be heard by

  1. dog

  2. bat

  3. rhinoceros

  4. human beings
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Rhinos have extremely good ears, picking up infra-sound far deeper than the range of human hearing.
Rhinos, can hear down to a frequency of four hertz, whereas even a human baby, with entirely undamaged ears, can normally only pick up sounds as low as 20 hertz. Giraffes and elephants can also hear in this infra-sound range.

Multiple choice how humans hear sound human ear study of sound sound physics

Combination of notes that produced jarring effect on the ear is called

  1. discord

  2. harmony

  3. noise

  4. melody
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Combination of notes that produced jarring effect on the ear is called discord. Discord is lack of harmony between notes sounding together.

Multiple choice how humans hear sound human ear study of sound sound physics

The persistence of hearing of human beings is not more than ________.

  1. 1 s
  2. $\displaystyle \frac{1}{5}$ s
  3. $\displaystyle \frac{1}{10}$ s
  4. $\displaystyle \frac{1}{2}$ s
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The sensation of hearing of any sound persists in our brain is 0.1 s. This is called the persistence of hearing. The persistence of hearing of human beings is not more than $\frac{1}{5}\,s$

Multiple choice how humans hear sound human ear study of sound sound physics

State whether true or false.

Vibration of the ear drum produces sensation of sound in the ears.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The sound waves produces vibration of the ear drum and subsequently a forceful vibration of the bones of the middle ear. This high amplitude vibration is transmitted to the fluid of the inner ear and encoded in the nerve signal which is sent to the brain.

Multiple choice how humans hear sound human ear study of sound sound physics

Select the loudness level that is above the normal hearing range

  1. 150 decibels

  2. 40 decibels

  3. 70 decibels

  4. 90 decibels
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In order for us to be able to hear a sound at all, it has to be above a certain level. This level is called the auditory threshold or hearing threshold. Humans have a hearing threshold of around $0$ decibels. Above this threshold, sounds with higher sound pressure levels are heard as louder noises. Sounds above $90\, dB$ can lead to chronic hearing damage if people are exposed to them every day or all the time. Hearing becomes uncomfortable if the sound pressure level is above $110$ decibels (threshold of discomfort), and it becomes painful above $130$ decibels (threshold of pain).

Multiple choice how humans hear sound human ear study of sound sound physics

Sound from the outside world reach the inner ear through:

  1. pinna

  2. cochlea

  3. auditory canal

  4. labyrinth
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Sound from the outside world are collected by pinna and reach the inner ear through auditory canal.

Multiple choice how humans hear sound human ear study of sound sound physics

The sound waves starts vibrating when it reaches:

  1. pinna

  2. stirrup

  3. tympanic membrane

  4. all
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

When the sound waves strike the eardrum or tympanic membrane it starts vibrating. Sound from the outside world are collected by pinna and reach the eardrum through auditory canal.

Multiple choice how humans hear sound human ear study of sound sound physics

The tympanum of the ear receive the sound in the form of_________.

  1. compressions

  2. rarefaction

  3. both

  4. none
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The tympanum of the ear receive the sound in the form of compressions and rarefaction. These compressions and rarefaction strike the ear drum, the ear from begins to vibrate.

Multiple choice how humans hear sound human ear study of sound sound physics

Mark the correct statement.

  1. Time taken by two consecutive compressions or one rarefaction is called the time period of the wave.

  2. Sound of a vollin and a flue are different due to the difference in the medium through which they travel.

  3. How the brain interpnetes the frequency of an emmitted sound is called pitch.

  4. All true
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Time taken by 2 consecutive compression or rarefaction is called the time period of the wave.
Sound of a voilin and a flute is different due to their different pitches.

Multiple choice how humans hear sound human ear study of sound sound physics

The compressions and rarefactions are transmitted across the middle ear through__________.

  1. auditory tube

  2. ear ossicles

  3. cochlea

  4. all
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The compressions and rarefactions are transmitted across the middle ear through the three ear ossicles. The vibrations produced in the ear drum are amplified.

Multiple choice how humans hear sound human ear study of sound sound physics

Which of the following order is correct?

  1. Sound $\rightarrow$ ear $\rightarrow$ inner ear $\rightarrow$ vibration of eardrum $\rightarrow$ brain $\rightarrow$ hearing
  2. Ear $\rightarrow$ Vibration of eardrum $\rightarrow$ Inner ear $\rightarrow$ hearing $\rightarrow$ brain $\rightarrow$ vibration
  3. Sound $\rightarrow$ ear $\rightarrow$ inner ear $\rightarrow$ vibration of eardrum $\rightarrow$ hearing $\rightarrow$ brain
  4. Sound $\rightarrow$ ear $\rightarrow$ vibration of eardrum $\rightarrow$ inner ear $\rightarrow$ brain $\rightarrow$ hearing
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

When sound strikes the ear drum, it vibrates and this vibration is carried to the inner ear from where it is carried to the brain in the form of impulse. The brain then gives the signal and we hear the sound.